I think the problem with using exhaust paste is it’s already started to harden during your first ride which means you never get to do that hot retighten.
I agree and it takes ages to pick the wretched stuff out of the threads. As gary says Its just not needed!
The check and re-tighten procedure of the exhaust nuts is in the user manual @500km and @2000Km, during running in,
but the wise would take that to mean also on exhaust removal or replacement.
We have improved that a little to say tighten when hot.
Hardening paste as Tom says has already gone hard after the first ride i.e before 500km.
Mark